How does sendmail work

If the application is unable to send the message, a failure message is returned to the sender to let them know that the message was never sent. Certain sections of email headers are unique information added by an organization, but other parts are always included when using Sendmail.

The following is the basic syntax of an email header value:. The field name-value pair must be on its own line, or the syntax validation step could fail, and outgoing messages will never be sent. Several security standards have been created for email to stop spoofing and phishing.

These security headers are also appended to outgoing messages to validate that the sender email address is legitimate and not spoofed. Cloud providers offer automated installation of the application making it easy for businesses and their administrators to set up an outgoing email server without knowing the configurations needed to set it up properly.

With a graphical user interface, users do not need to use the command line to send an email. A Sendmail-installed server can also handle outgoing email messages from a web application.

For businesses with virtual machines and their own web servers, Sendmail must be installed on the server, but most web hosts include the installation in cPanel. Any automated installations do not require manual configurations. Sendmail is a backend service, so its operations are invisible to an end-user.

Should an administrator decide to test Sendmail from the command line, several options and commands are available, but the basic syntax to send a simple message as follows:. Typing the above command activates Sendmail so that an email can be sent to the given address. As an example, the following input sends an email from me me. Show Posts. Registered User.

Join Date: Feb Excuse me for this question really for dummies! I would like to know how sendmail works, obviously even in few words. If it uses a mail server or relay to send mail, if there is some check that sendmail makes to the from address and so on Thank you very much. Join Date: Aug Please search the forums first. Your best bet for all-around knowledge is probably to go to www. There's also an faq for that.

Join Date: Apr Buy the book - it is invaluable. Check out the Sendmail FAQ. Join Date: May Sendmail is a huge beast and to tackle what it is and how it works i think is beyond this forum. Clarifying sendmail configuration - sendmail-client offline. Hi all, I have read about sendmail running as 2 separate process. In my current configuration, the sendmail-client is disabled. Both submit. Sendmail questions, SCO 5.

I am running SCO 5. When trying to send mail the following message will kick back. The sendmail program never edits or changes the body of a message. Sendmail receives mail for local system user login accounts. Steps to run mail server using sendmail: Required for inbound mail: The mail server must be identified by the DNS as the mail server in order to receive mail. A look at MailRadar. In comparison to other MTAs, Postfix emphasizes security. Postfix is much more secure than Sendmail, which has weak security architecture.

Postfix is designed to overcome the vulnerabilities that are associated with Sendmail. Moreover, a good Postfix configuration secures sensitive data from spam, abuse, and leakage. To check what is currently sitting in the sendmail mail queue use the sendmail -bp command or its alias mailq.